RSN Fundraising Banner
FB Share
Email This Page
add comment

Giggs writes: "Blue whales, Earth's largest animals, call to others of their kind, though exactly what these cries communicate remains a mystery."

A blue whale. (photo: National Geographic)
A blue whale. (photo: National Geographic)

Whale Songs Are Getting Deeper - All Theories Why Involve Humans

By Rebecca Giggs, The Atlantic

08 September 19


s any environment more secluded from our imagination than the seas surrounding Antarctica? Icebergs grind above a seabed dotted with salps, sea squirts, sponges, and other barely animate organisms. The sun scarcely rises for half the year. Under the elemental conditions at these latitudes, Antarctic blue whales exist in a world defined by bioacoustics. Blue whales, theories as to why—some worrisome, some hopeful, all involving humans.

The deepening of Antarctic blue whales’ sounds is not unique to the subspecies. Groups of pygmy blue whales found near Madagascar, Sri Lanka, and Australia, as well as fin whales, which live in seas around the world, have also dropped their pitch. (Even before this change, fin whales emitted sounds so low as to be nearly imperceptible to humans; the wavelengths of their calls were often longer than the bodies of the whales themselves.) In a study last year that analyzed more than 1 million individual recordings of whale calls, scale shifts were found across species, and among populations that don’t necessarily interact with one another. Which is to say, whatever has triggered the change doesn’t seem to have a specific geographic origin.

The underwater clamor caused by maritime traffic and extractive industries might seem a likely culprit. After all, such noise is known to identified lowered pitches even across populations of whales that live in seas without major shipping routes, where mechanical noise is negligible.

Another possible explanation for the change in whale calls is the achievements of global conservation efforts. At the start of the 20th century, an estimated 239,000 Antarctic blue whales occupied the Southern Ocean. By the early 1970s, decades of commercial whaling—initially by Norwegian and British whalers, and later by illegal Soviet fleets—had decreased the blue-whale population in the region to a mere 360. But since protection of the subspecies began in 1966, that number has begun to rebound. Scientists have speculated that the whale’s anatomy determines that the louder it gets, the higher the pitch of its calls. As populations have grown, then, the whales may have decreased their volume because they are more likely to be communicating over short distances. In other words, Antarctic blue whales may be lower-toned today than in previous decades simply because they no longer need to shout.

Last year’s study of whale calls also suggests a more ominous reason for the drop in pitch, however: Perhaps whales don’t need to be so loud because sound waves travel farther in oceans made acidic by the absorption of carbon dioxide.

Carbon dioxide in the atmosphere, meanwhile, may indirectly influence whale voices in other ways. Recent monitoring of Antarctic blue whales shows that, during the austral summer, their pitch rises. Researchers have hypothesized that in warmer months, the whales must use their forte volume to be heard amid the cracking ice—a natural sound amplified by unnatural processes, as rising temperatures exacerbate ice-melt. So the impacts of a warming planet may modulate animal sounds even in remote places with barely any humans, and where the most thunderous notes come not from ships, but from the clatter of breaking ice.

We may not yet know what the sounds of blue whales mean. But whether through our intent to preserve these creatures, or as a result of refashioning their environment, our deeds echo in their voices. your social media marketing partner
Email This Page


THE NEW STREAMLINED RSN LOGIN PROCESS: Register once, then login and you are ready to comment. All you need is a Username and a Password of your choosing and you are free to comment whenever you like! Welcome to the Reader Supported News community.